Comparative Parasitology 67(1) 2000 - Peru State College

quadrant and 70° in male, 75° in female in dorsal
left quadrant. Ridges of equivalent size, except
ventral right ones and ventral ridge adjacent to
left ridge, all of which are smaller (Figs. 5, 6).
MALES (based on 5 specimens): Length
3.75-6.3 mm (6.4 mm) and width 90-100 (100)
at mid body. Cephalic vesicle 50X40-60X40
(60X45). Nerve ring 120-170 (160), excretory
pore 160—250 (230) from cephalic apex, respectively.
Esophagus 350-380 (380) long (Fig. 1).
Caudal bursa subsymmetric, very elongated laterally,
of type 2-2-1 (Fig. 8). Rays 2 and 3 longer
than ray 4; rays 4 and 5 divergent at their
extremities; ray 8 arising perpendicularly at the
root of the dorsal ray and not reaching edge of
bursa; dorsal ray divided into 2 branches in distal
third, each branch divided again into 2 unequal
branches; externals (ray 9) being longer
than the internal (ray 10), and almost reaching
edge of caudal bursa. Spicules very thin, alate,
380-500 (460) long, ending in a sharp tip (Fig.
8). Gubernaculum absent. Genital cone triangular
in ventral view, bearing a small papilla 0 on
its ventral lip (Fig. 7). Papilla 7 not observed.
Presence of membrane situated between genital
cone and dorsal ray (Fig. 8).
FEMALES (based on 10 specimens): Length
7.3-8.8 mm (7.3 mm) and width 110-150 (150)
at mid body. Cephalic vesicle 50X40-80X60
(60X50). Nerve ring 130-220 (160), excretory
pore 175—320 (210) from cephalic apex, respectively.
Esophagus 420-480 (450) long. Monodelphic,
vulva at 110-160 (100) from caudal extremity.
Vagina vera 30—50 (40) long. Vestibule
80—110 (70) long, with median constriction and
posterior diverticulum, sphincter 40X30-50X40
(50X40). Infundibulum with proximal section
curving in and out (twisting) 90-130 (120) (Fig.
4). Uterus 1.2—1.8 mm (1.7 mm) long, containing
30-36 (25) eggs. Eggs 65X40-80X60
(85X50) at morula stage. In 1 female, eggs in
distal section of uterus embryonated. Tail conical,
with round tip (Fig. 4).
Taxonomic Summary
TYPE HOST: White-ankled mouse, Peromyscus
pectoralis Osgood, 1904.
TYPE LOCALITY: Colorado Bend State Park,
San Saba County, Texas (31°05'N, 98°30'W),
U.S.A.
SITE: Small intestine.
PREVALENCE AND INTENSITY: 57 of 189 hosts
DURETTE-DESSET AND SANTOS—CAROL1NENSIS TUFFI SF'. N. 67
(30%) infected with 11.2 ± 3.3 SD nematodes;
range, 1—175.
DEPOSITED SPECIMENS: Holotype male and
allotype female MNHN 447 KXa; paratypes (4
males, 9 females) MNHN 447 KXb.
ETYMOLOGY: The species is named in honor
of Dr. Donald W. Tuff of Southwest Texas State
University.
Discussion
The specimens from P. pectoralis possess the
main characters of the subgenus Carolinensis
(Heligmonellidae: Nippostrongylinae), which
was raised to the level of genus by Durette-Desset
(1983): the caudal bursa is of type 2-2-1,
the genital cone is poorly developed, and the left
cuticular dilatation is absent. Species of this genus
are mainly parasitic in Holarctic Arvicolidae
and Cricetidae. Among the species described,
the above specimens closely resemble Carolinensis
carolinensis (Dikmans, 1935), a parasite
of Peromyscus maniculatus (Wagner, 1845) and
Microtus ochrogaster (Wagner, 1842) in the
United States in the characters of the synlophe;
the left lateral ridges are no more developed than
the other ridges, the inclination of the axis of
orientation is the same, and the number of cuticular
ridges is relatively high. The new species
differs by the pattern of the caudal bursa, the
shape of the tips of the spicules, and 19-20 ridges
versus 16 in C. carolinensis (Durette-Desset,
1974). It closely resembles Carolinensis dalrymplei
(Dikmans, 1935), a parasite of Ondatra zibethica
(Linnaeus, 1766) and Microtus pennsylvanicus
(Ord, 1815) in the United States and
Carolinensis kinsellai (Durette-Desset, 1969), a
parasite of Neofiber alleni True, 1884, in the
United States, in the pattern of the caudal bursa
and, as in C. kinsellai, by the presence of a small
ventral ridge adjacent to the left ridge. It differs
from these species by the arising of ray 8 at the
root of the dorsal ray, by the presence of a membrane
between the genital cone and the dorsal
ray, by the proximal twisting of the infundibulum,
and by the high number of cuticular ridges
(13 in C. kinsellai, not known in C. dalrymplei)
(Durette-Desset, 1969).
According to Durette-Desset (1971), the genera
Carolinensis, Hassalstrongylus, arid Stilestrongylus
belong to the same evolutionary line.
The line may have arisen in the Palearctic Region
and may have evolved from North America to
South America with the following elements: (1)
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